It is known that metals, including metal alloys (either crystalline or amorphous), may be electrodeposited upon a surface of a substrate so as to form a plating, coating or layer of the metal thereon. In recent years, electrodeposition processing has been utilized so as to produce orifice plates suitable for use in fluid jet printing devices, as is disclosed in U.S. Pat. Nos. 4,229,265 and 4,528,070. Electrodeposition of metals to form orifice plates is a desirable technique since it is critically important that the apertures of the orifice plate be formed within very close spatial and alignment tolerances. Otherwise, fluid droplet streams which issue from misformed or misaligned apertures are skewed relative to other droplet streams, thereby degrading the resulting print quality. Electrodeposition techniques, to a large extent, ensure that such close spatial and alignment tolerances are observed when used to produce orifice plates for fluid jet printing devices.
By means of the present invention, process and apparatus have been provided whereby a layer of a metallic substance may be electrodeposited upon a surface of a substrate, the deposited layer then preferably being separated from the substrate so as to form a monolithic (i.e. self-supporting) "foil" of the deposited metal. The substrate onto which the metal is to be electrodeposited is, according to this invention, formed into a cylindrical configuration and is immersed in a liquid electrodeposition bath containing ions of the metallic substance to be electrodeposited onto the substrate's exposed surface. The substrate, acting as a cathode, is then rotated in the bath about the axis of its cylindrical configuration while the electrodeposition process is occurring so as to expose the substrate surface to a substantially uniform electric field and to expose all of the substrate surface to the liquid in the bath. In such a manner, a layer having a uniform thickness (usually a few mils) of the metallic substance may be formed onto the substrate surface, the deposited layer being subsequently separated from the substrate so as to provide a self-supporting foil of the desired metal.
This invention may therefore be utilized to produce orifice plates suitable for use in fluid jet printing devices by masking an array of circular areas on the substrate's plating surface by well known photoresist techniques so as to prevent electrodeposition of the metal thereat. Upon separation of the deposited metal layer (to obtain a "foil" or "plate" of the deposited metal) from the substrate, apertures corresponding to the masked areas of the substrate's surface will be present in the removed metal layer. The present invention is therefore advantageously utilized so as to form "monolithic" orifice plates, that is to say, an orifice plate which is self-supporting (i.e. does not depend upon an underlying substrate for its mechanical support).
Since the foil will be self-supporting, there must be sufficient thickness to provide the necessary inherent mechanical support. Preferably, the orifice plates which can be produced by this invention have thicknesses of greater than 1.0 mil., and more preferably, not greater than about 2.5 mils. Of course, other thicknesses of the resulting foil are possible in dependance upon the duration of the electrodeposition process.
The metal to be deposited upon the substrate in accordance with this invention is preferably a ductile amorphous nickel-phosphorus alloy of the type disclosed in copending, commonly owned U.S. application Ser. No. 923,270 filed Oct. 27, 1986 in the name of John A. Lichtenberger (the entire disclosure thereof being expressly incorporated hereinto by reference). Such amorphous nickel-phosphorus alloys exhibit advantageous ductility which facilitates the alloy's separation from the underlying substrate and further handling of the resulting foil without being damaged.
Further advantages and details of this invention will become more clear after consideration is given to the detailed description of the invention which follows.